The growing importance of alternative energy sources has brought a renewed interest in the Fischer-Tropsch synthesis as one of the more attractive direct and environmentally acceptable paths to high quality transportation fuels. The Fischer-Tropsch synthesis involves the production of hydrocarbons by the catalyzed reaction of CO and hydrogen. Commercial plants have operated in Germany, South Africa and other parts of the world based on the use of particular catalysts.
The use of promoted cobalt catalysts has attracted wide attention. For example, the German commercial operation concentrated on the use of a precipitated cobalt-thoria-kieselguhr fixed-bed catalyst, and a later modification in which MgO, for economy reasons, replaced part of the thoria.
More recently, U.S. Pat. No. 4,088,671 to T. P. Kobylinski describes the use of a ruthenium-promoted cobalt catalyst on a support, such as alumina or kieselguhr, in the synthesis of hydrocarbons from the reaction of CO and hydrogen at substantially atmospheric pressure. As ruthenium is expensive, the patent indicates that it is preferred to employ ruthenium in the minimum amount necessary to achieve the desired result.
Attempts have been made to utilize unpromoted cobalt catalysts for the synthesis of hydrocarbons from synthesis gas. However, unpromoted cobalt often had poor selectivity and requires high metal loadings to provide desirable activity.